Thermodynamical aspiration valve

ABSTRACT

An aspirating thermodynamic valve capable of controlling the flow of fuel mixture and air from the carburetor to the crankcase of a two-stroke engine includes a hollow body placed between the joint of the crankcase and the joint of the carburetor, along with suitably interpositioned seals. The valve includes a bush, the extremity of which is placed inside of the body and is cut out according to a predetermined inclination; furthermore, it includes a wall which is hinged by one end and is capable of closing the extremity.

TECHNICAL FIELD

This invention relates to a thermodynamic aspirating valve.

More specifically, this invention relates to a thermodynamic aspiratingvalve for controlling and regulating the flow of fuel to the carburettorand to the crankcase of a two-stroke engine.

This invention can be applied specifically in the mechanical andautomotive industry.

BACKGROUND ART

In the two-stroke engines known at present, the piston opens and shutsthe aspiration inlet; therefore, the control of the mixture flow issymmetric relative to the two return positions.

The angle between the beginning of the opening of the aspiration inletand the return position of the piston is equal to the angle between thereturn position and the end of the closure of the aspiration inlet.

In typical two-stroke engines the full angle of the opening of theaspiration inlet is contained within 100° and 110° of the cam shaftrotation; the half of the angle corresponds to the rotation of thepiston in the external direction and the other half corresponds to thereturn of the piston.

It has been observed that the symmetrical control of the flow of fuel tothe crankcase is not a good solution as the aspiration inlet should openmuch earlier and close later and this is not possible with thetraditional piston position.

To avoid this inconvenience a solution has been adopted, according towhich circulation of gas is made independent from the piston movementswith a rotary throttling valve mounted on the cam shaft.

This valve allows a symmetrical inflow of fuel to the crankcase while itis opened and shut by a rotary plate.

This plate is cut accordingly to the angle corresponding to the angle ofthe opening of the aspiration inlet and the inflow of fuel to thecrankcase is dependent on the size of the aspiration inlet.

Other known solutions allow automatic control of the inflow of fuel bythe alteration of pressure in the crankcase.

For this purpose plate valves are applied that consist of springingplates interconnected in parallel.

Due to the pressure within the crankcase, these plates move awayproportionally to the depression value which allows the fuel inflow.

When the balance of pressures is achieved the plates shut the aspirationinlet without allowing the fuel to return.

A system of this kind is based on a mode of mechanical control of theinflow of fuel to the crankcase and, in the case where rotary plates areused, the construction of the engine is complicated, which increasescosts of production.

Another disadvantage of these systems arises from the fact that theiraccurate functioning takes place only if the r.p.m. value of the camshaft rotation is strictly specified, which renders them virtuallyinapplicable; therefore, such systems practically are not employed incircuit racing engines and rally engines.

In the case where the plate valves are used, proper functioning andcapacity of those depend on the materials from which they aremanufactured.

Nevertheless, considering the fact that the plates are mounted rigidly,they do not sustain prolonged strain and are deformed and worn out,which causes breakdown that, in turn requires frequent replacements.

Additionally, operation of the plates prohibits, due to internalreactions, the slow inflow of fuel to the degree in which the increasingresistance of the plates does not allow the fuel to inflow when it ismost demanded.

The above solutions have other disadvantages, such as unsolved problemof uneconomical fuel consumption and high degree of environmentalpollution which are caused by the two-stroke engines.

However, the pollution produced by two-stroke engines is generallycaused by faulty fuel supply during the work cycle.

Actually, the combustion chamber is flooded with fuel that cannot befully consumed, i.e. burnt up, during the only two strokes of the cycle.

Due to the above, the application of two-stroke engines has beensignificantly reduced lately in spite of their cost-effectiveconstruction and economical operation.

U.S. Pat. No. 4,356,798 discloses an aspirating thermodynamic valvecapable of controlling the flow of fuel mixture and air from thecarburettor to the crankcase of a two-stroke engine. Said valvecomprises a hollow body suitable for being placed between the joint ofthe crankcase and the joint of the carburettor, along with suitablyinterpositioned seals, a bush, the extremity of which is placed insideof said body and cut out according to a predetermined inclination, andcomprising a wall which is hinged by one end and is capable of closingsaid extremity.

U.S. Pat. No. 5,390,633 discloses the arrangement of an aspiratingthermodynamic valve between the crankcase of an engine and thecarburettor, and exhibiting a bush, the extremity of which is placedinside of the crankschaft intake body and is cut out according to apredetermined inclination, and comprising a wall which is hinged by oneend and is capable of closing said extremity.

DE-A-3,741,880 suggests a valve in which a wall is made of ferromagneticmaterial and an electromagnet is mounted on the valve body. In this casethe attraction force is designed for opening the valve and not forreturning the wall in the position of closure as described in thepresent invention.

DESCRIPTION OF THE INVENTION

The present invention aims to obviate to the disadvantages andinconveniences mentioned above, and to provide for a thermodynamicaspirating valve which allows, in the case where it is used intwo-stroke engines, a specific amount of fuel required to combust,causing the increase of power assessed at about 50%, and reduction ofcombustion assessed at about 50%.

This is accomplished with a valve having the features described in themain claim.

The dependent claims outline advantageous forms of embodiment of theinvention.

The proposed solution of this invention is based on thermodynamics laws(H. Faltin, "Technische Thermodynamik", Berlin 1961, W. R. Grundlach,"Einfuhrung in die Technische Thermodynamik", Zurich 1947, A. Hall, E.Ibele, "Engineering Thermodynamics", Prentice Hall 1960), and is simplyconstructed and may be commonly used.

According to the invention, the thermodynamic aspirating valve containsa suitably articulated wall which closes a bush cut at an angle andoperates according to the principle of a inclined Bendemann's nozzlethat provides the variable ratio of the aperture (opposed to theconstant ratio of the aperture possible to obtain e.g. in Laval'snozzle) dependent on the pressure in the crankcase.

Thus, the mechanical controlling of the fuel inflow to the crankcase isavoided.

The fuel flowing through such a nozzle, with a variable ratio of theaperture, constitutes a diasonic flow at the subsonic velocity.

Consequently, at the inlet of the inflow to the crankcase a phenomenonof dynamic Rankin-Hugoniot occurs and decompression of the gascoefficient is adjusted to any depression.

The flow of fuel mixture as diasonic flow depends on the rotation speedof the cam shaft. This fact does not allow the flow to separate from theaspiration pipe walls.

The above phenomenon prohibits whirl creation and the flow of gas comingout from the valve expands, prohibiting the return of the fuel duringthe full rotation cycle of the cam shaft.

According to the invention, the flow of fuel supplied to the crankcasethrough the valve wall is vibratory (which corresponds to the kineticgas theory).

The above takes place within limits of the cam shaft rotation. The wallthat shuts the inclined nozzle of the variable ratio of the aperturedivides the fuel inflowing to the crankcase into portions and so atevery stroke of the aspirating piston occur some of the supply cycles(from a pair to ten or more depending on the engine cubic capacity), ateach subsequent cycle an energetic level higher to the precedent cycleoccurs (the catapult phenomenon).

These cycles which divide the aspirating movement of the piston intomore periods can be explained by means of laws of physics, in the momentin which the depression in the crankcase reaches values higher to theinertia mass of oscillating wall, the latter is opened and the fuelmixture is injected into the crankcase.

According to the invention, the oscillating movement of the wall islimited by a suitable buffer placed in the valve bush, this buffer beingprovided with elastic means suitable for attenuation of strokes comingfrom the wall.

Afterwards, at the opening of wall the latter is pushed against thebuffer, rebounces from it coming into the shut position and temporarilybreaking the flow of the fuel mixture.

During the return stroke, however, the wall encounters the flow of fuelwhich flows through the nozzle according to the Coulomb law and exertspressure on the flow itself.

In practice, it may happen that the wall shuts progressively and,therefore, according to the Bernoulli law, the flow of the fuel mixturebecomes faster reducing, at the same time, the pressure; thisphenomenon, which occurs during the full period of the cam shaftrotation in the return compression mode, continues until the fullclosure of the wall.

At this moment the depression within the crankcase overcomes the forcewhich holds the wall in place and the wall opens again initialising anew cycle.

According to an essential feature of the invention, the return movementof the wall is allowed by the operation of a permanent magnet, the powerof which draws the wall into the shut position.

The aspirating valve, according to the invention, applying thethermodynamics laws, directly influences the efficiency of thetwo-stroke engine.

Tests conducted by the applicant have proven a fuel save up to 50%, asfar as fuel consumption is concerned and comparable increase of power.

It has been also determined that the lifetime of the engine increases,contrary to what may be expected due to scarce lubrication caused by thereduced inflow of the fuel mixture.

The above fact occurs because the removal of the combustion residues isimproved, as well as the intensity of the internal cooling thanks toelastic suffocation of the mixture, which behaves similarly to theliquids in Linde's coolers.

Therefore, the twostroke engine provided with the valve, according tothe invention, does not overheat even at high ambient temperatures andin cases of full load, and even the self-ignition does not occur;besides, serious defects of the bridge at electrodes of sparking plugsdo not occur that are typical for two-stroke engines.

Finally, a significant increase flexibility of the engine may beobserved.

ILLUSTRATION OF FIGURES

Other features and advantages of the invention will become apparentwhile reading the following description, which has been given as anon-limiting example, with the help of the figures illustrated in theattached drawings, in which:

FIG. 1 shows a schematic side section of the aspirating valve, accordingto the invention

FIG. 2 shows a plan section, made along the A--A line, of the valveaccording to the FIG. 1.

DESCRIPTION OF A FORM OF EMBODIMENT

In the figures, a thermodynamic aspirating valve for a two-strokeengine, according to the invention, includes a body 4, inside of whichis seated an inclined bush that has a nozzle or neck 11, the mentionedbody being inserted between the junction 1 of the cylinder or crankcaseand the junction 7 of the carburettor with the interposition of therespective seals 8 and 12.

A wall 10 inclined according to a predetermined angle is mounted abovethe neck 11; this wall 10 is movable around an axis defined by a coupleof pivots 5.

Moreover, corresponding to the wall extremity 10, being at a distancefrom the bolts 5 there is a weight 9 which is selected depending on thetechnical characters of the engine.

As shown in FIG. 1, wall 10 is mounted and inclined according to apredetermined angle, for instance positioned at approximately 45degrees, forming a Bendemann's nozzle having a variable ratio ofaperture.

Seal 6 is mounted between body 4 and neck 11 along the edge of body 4.

According to the invention, a telescoping bumper element 2 is mountedinside of body 4; such bumper element consists of a sleeve threaded onits total length in order to regulate its position and has at itsextremity resilient means 3, for instance a spring which fulfills doublefunction of amortisation of the stroke of the wall 10 when the latter isfully opened, and the second function is exerting on the same wall apressure which strains to draw wall 10 towards its closed position.

Finally, the valve is fixed to the engine body and to the carburettor bymeans of screws 13 (see FIG. 2).

An aspirating valve of this type allows gaining all advantages describedabove, to the extent at which the latter is easily adjustable to anytype of a two-stroke engine, thanks to maximal aperture by means ofbumper element 2.

As a result, an ideal filling of the crankcase with fuel can beachieved.

According to an essential feature of the invention, wall 10 is made of aferromagnetic material, and a permanent magnet (not illustrated in thefigures) is inserted below the body 4 of the valve.

Such a magnet exerts a permanent force of attraction relative to wall 10attracting the latter to the closing position, it dampens the vibrationsand it enhances the comeback of the wall after the stroke against thebumper.

Moreover, the potential of the applied magnetic field, beside amechanical operation on the wall, acts also electrostatically on thechemical and physical structure of the fuel mixture flow, since a strongelectrostatic field is induced on the edge of the wall which isvibrating in the magnetic field.

Such a field causes an acceleration effect on the electrons which, whilestriking air particles of the fuel mixture, liberate more loadedparticles; then, the main charge on the edge of the wall attracts a partof such particles that, being of an opposite sign, neutralise the chargeat the edge of the wall.

Conversely, particles of the same sign as these of the charge at theedge of the wall are rejected and carry with them a part of the mixture,thereby forming an electrical wind.

At the same time, the electrostatic field induced at the edge of thewall has an opposite sign in respect of the field induced between theelectrodes of the plug that forms a spark in the particles ionised bythe gas.

The opposed charges of the fields cause then electrostatic attractionand maximal condensation of loaded particles of fuel around theelectrodes of the plug either before the spark forms or during theperiod of spark ignition, which affects economical consumption of fueland the increase of engine power.

In the meantime, a particular inertia of particles of fuel in relationto electrostatic forces causes the elimination of the part of electricalcharges, which reduces their superficial strength and increases thediffusion coefficient; thereby, the combustion time is reduced and theintensity of the combustion increased.

I claim:
 1. Aspirating thermodynamic valve capable of controlling theflow of fuel mixture and air from the carburettor to the crankcase of atwo-stroke engine, comprising a hollow body to be placed between thejoint of the crankcase and the joint of the carburettor, along withsuitably interpositioned seals, a bush, the extremity of which is placedinside of said body and cut out according to a predeterminedinclination, and a wall which is hinged by one end and is capable ofclosing said extremity, wherein said wall is made of ferromagneticmaterial and in that a permanent magnet is mounted on the body of thevalve in correspondence of wall in order to carry out on said wall aforce of attraction which holds the wall in the position of the closureof the mentioned bush.
 2. A valve as claimed in the claim 1, whereinsaid wall carries a weight in correspondence of its extremity placedaway of the hinge.
 3. A valve as claimed in claim 1, wherein the valvecomprises means capable of limiting the movement of aperture of thewall.
 4. A valve as claimed in claim 3 wherein said means comprise atelescoping bumper element, on the extremity of which there areresilient means advantageously consisting of springs, capable ofdampening the stroke carried out by the wall during the run of itsopening movement.
 5. A valve as claimed in claim 2, wherein the valvecomprises means capable of limiting the movement of aperture of thewall.
 6. A valve as claimed in claim 5 wherein said means comprise atelescoping bumper element, on the extremity of which there areresilient means advantageously consisting of springs, capable ofdampening the stroke carried out by the wall during the run of itsopening movement.